The invention relates to a method for producing a plastic component with an internal hollow space, wherein at first plastic is injected into an injection mold, gas is then introduced into the liquid plastic melt to displace the melt from the internal hollow space to be formed under pressure, and then for cooling the plastic, a liquid is introduced into the internal hollow space.
The invention further relates to a device for producing a plastic component with an internal hollow space using an injection mold, which can be connected to an injection-molding machine and which has a connection for introducing gas for displacing melt from the internal hollow space to be formed in the component and for introducing a cooling liquid, especially water.
A similar method and a device of this general type are known from DE 199 29 700 A1. According to this known method, at first after the injection mold is filled with the plastic material or the plastic melt, a gas volume is introduced through an inlet opening for forming the hollow space, whereby this gas volume is discharged again from the hollow space by means of a different opening. Thus, this gas must be introduced at a sufficient pressure, i.e., a corresponding device for generating the gas pressure is required to inject the gas into the injection mold.
In this known method, after the gas is discharged, at first the inlet opening is made larger in terms of its flow cross section to allow the cooling liquid to be introduced at a regulated pressure and/or volume. Thus, the cooling liquid also requires a corresponding feeding or pressure device, thus it requires relatively large machine expense.
In addition, there is no way to stop the still plastic mass located in the interior of the injection mold from beginning to flow due to the influence of gravity during the time between when the gas is discharged and the cooling liquid is introduced. Thus, it is possible that in this intermediate time before the cooling liquid takes effect, the internal hollow space of the component could change in an undesired way.